Moving Green Dots Optical Illusion

Can you see how this optical illusion moves and shifts?

Since we live in a three dimensional world, our mind tries to convert a two dimensional object into a 3-D one. In this optical illusion, our mind tries to make sense of these 2-D objects. The shading used here is completely incongruous. We lock onto a bit of the illustration that looks appropriately shaded but then find it disjointed with shading in other nearby areas. The eyes keep jumping around the drawing trying to map out a 3D solution that would make the shading illustration make sense, but it we can't.